The specific 'aim of the ASPEN CANCER CONFERENCE is to provide an interchange whereby a group of investigators in areas related to cell growth and differentiation, proto-oncogenes, tumor suppressor genes, cell toxicity discuss new research findings, examine new concepts, nd develop new research strategies. Aspects of mechanisms of tumor promotion and enhancement are reviewed in detail and the relationship between toxicity, promotion, and both genotoxic and non-genotoxic carcinogens re explored. How these findings relate to consideration of human safety assessment are considered. Potential new therapies based upon differentiation control may also emerge. Presentations will be given by leading scientists followed by vigorous discussions of these presentations by a mix of scientists from various disciplines and with unique experiences which will provide an intellectual forum to aid in the exchange of information between basic and regulatory science.